Health literacy has emerged as a critically important factor in health outcomes. Although existing measures of health literacy have distinct advantages and have been useful in research and clinical practice, each has characteristics that reduce its usefulness with some populations. The core aim of this application will be to develop a new health literacy measure with content, linguistic, and psychometric properties that will make it more broadly useful for screening and diagnostic purposes in clinical and research populations. It will be administered using computer touch screen technology to make the measure easily administered and scored and readily accessible via computers or the Internet. During development the measure will be validated by assessing its relations to other measures and participants' health. The planned development process will use item response theory (IRT) methods to develop a measure that functions equivalently in both Spanish and English and with younger and older persons. Its content will be broadly based following the recommendations health literacy experts and include audio and video items to enhance the measure's interest and validity. The measure will be computer administered using touch screen technology so that when deployed it may be self-administered and scored. The measure will be developed in two phases. We will first generate approximately 200 candidate items by rationally creating items of various levels of difficulty within broad content areas related to health literacy based on the content areas described in the Institute of Medicine report on health literacy (Nielsen-Bohlman et al., 2004). Items will be generated in Spanish or English and then translated and back translated into and from each language to ensure that their content is equivalent in both languages. We will then pilot test these candidate items in Spanish and English with 75 persons from each language group across several age ranges, drawing on persons aged 18 years and older. Items will be qualitatively evaluated using participant feedback and quantitatively using nonparametric IRT methods Items will be selected from the larger item pool for testing with larger groups of 30 persons in each decade of age from the 20s to 80s in both Spanish and English, so that 60 persons in each decade will be involved in the second phase of scale development for a total of 420 persons. The measure will be validated by assessing its relations with currently-used measures of health literacy, cognitive and academic measures, and health status, health care-related quality of life, and utilization of healthcare services. The creation of an easily-administered measure of health literacy will further the goals of this program announcement that requests applications focused on improved measures of health literacy. The new measure will be readily deployed over the Web. Future development will allow the creation of a computerized adaptive measure of health literacy and integrated tailored information applications to improve health literacy.